Hi, I'm using an Arduino Nano Every for a project and need to use the sleep and interrupt libraries.   The Arduino documentation says "AVR libraries have the potential to greatly extend the Arduino language....".  The AVR-LibC library contains both sleep and interrupt libraries.  In the past, I've found .zip files of libraries I wanted to load and can use the library manager to load them.  However, the AVR-libc on GitHub is way more than just libraries and there isn't a single .zip file. 

I would appreciate it if someone would give me detailed instructions on how to install these or point me to the detailed instructions.  Many thanks.....jimf